Yes there is a way of taking them off though it's not an easy job.
First wind the backrest of the seat forwards and push the whole seat forwards on the rails. At the bottom of the fabric you'll see a plastic strip which with a bit of force (flat bladed screwdriver) will first slide from side to side but it should come apart.
lying on the back seat wriggle your arm up the back of the seat and find the stalks that have the headrest on them. There is a metal clip that you have prise apart/away from the stalk and with the other hand push the headrest off.
Fit the seat covers and it's really a reverse to get them back on. I found a friend to help to put them back on as it's not easy opening the clip and pushing down on the headrest at the same time.
Remember to connect the plastic strip back together before you tie-up underneath. [source]